To accommodate the ever increasing mobility of users of radio pagers, the Federal Communications Commission (FCC) has allocated a number of frequencies in the 900 MHz band as nationwide paging channels. Users carrying pagers tuned to a nationwide channel can then receive personal page messages virtually anywhere in the U.S. However, to alleviate congestion and avoid delays in the nationwide transmissions of page messages, it is desirable to limit use of the nationwide paging channels to page messages for users who are actually traveling beyond the coverage or reception areas of the local paging systems to which they subscribe. It has therefore been proposed to require users to notify their local paging systems that they wish to receive radio page messages while traveling beyond their local reception area during specified travel periods, and only during the specified travel periods will page messages addressed to these traveling users be transmitted over a nationwide
Since nationwide paging channels and local paging channels operate at different radio frequencies, a pager user (or subscriber), desiring both local and nationwide service must either carry two pagers, one tuned to a nationwide channel and the other tuned to the user's local channel, or a single pager having the capability of switching between the nationwide and local channel frequencies. Naturally, the channel-switching single receiver is the preferred option for convenience sake. It is also generally preferable that the single pager have automatic channel switching capability, rather than requiring the user to remember to manually switch the pager between the nationwide and local paging channels as appropriate to the user's location.
A prime consideration of all pager users is, of course, that they faithfully receive all page messages addressed to them, regardless of whether they were transmitted over the local channel or a nationwide channel. This requires that users strictly adhere to any travel schedule filed with their local paging system terminal. If a user leaves the local coverage area prior to the scheduled departure time, the user cannot receive page messages because he or she is out of range of the local paging channel, and the page message will not have been transmitted on a nationwide channel. If the user leaves later than the scheduled departure time, page messages will be missed unless the paging receiver is tuned to a nationwide channel. Similarly, a return to the local coverage area ahead of schedule will result in missed page messages, unless the paging receiver is tuned to the nationwide channel, and a late return will result in the failure to receive page messages that were broadcast over the local channel prior to the user's return.
Page messages can also be missed when a user is traveling in the ill-defined outskirts of the local paging terminal's broadcast coverage area. Obviously, if the subscriber strays beyond the local broadcast coverage area, page messages broadcast over the local paging channel will not be received. When the user strays back into the local coverage area, a page message will be missed if the pager had been automatically switched to a nationwide channel frequency.